2.6 Statistical analysis
The differences in the physiological and biochemical properties of the V. natans samples among different groups were determined by one-way ANOVA and Tukey’s test using SPSS 20.0 software (P<0.05). Detrended correspondence analysis (DCA) (Canoco 4.5) was used to examine the correlation between different substrate and physiological characteristics of the plant. Since the length of the gradient value obtained by DCA in this study was less than three, the redundancy analysis (RDA) was further conducted.